The present invention relates to inkjet printing devices. More particularly, the present invention relates to an apparatus and method of using ultrasonic energy to fix ink to print media.
Inkjet printing devices use ink to print text, graphics, images, etc. onto print media. Inkjet printers may use print cartridges, also known as "pens", which shoot drops of ink onto a print medium, such as paper or transparencies. Each pen has a printhead that includes a plurality of nozzles. Each nozzle has an orifice through which the ink drops are fired. To print an image, the printhead is propelled back and forth across the page by, for example, a carriage, while shooting drops of ink in a desired pattern as the printhead moves. The particular ink ejection mechanism within the printhead may take on a variety of different forms known to those skilled in the art, such as thermal printhead technology. For thermal printheads, the ink may be a liquid, where dissolved colorants or pigments are dispersed in a solvent.
In a current thermal system, a barrier layer containing ink channels and vaporization chambers is located between an orifice plate and a substrate layer. This substrate layer typically contains linear arrays of heating elements, such as resistors, which are energized to heat ink within the vaporization chambers. Upon heating, the ink in the vaporization chamber turns into a gaseous state and forces or ejects an ink drop from a orifice associated with the energized resistor. By selectively energizing the resistors as the printhead moves across the print medium, the ink is expelled in a pattern onto the print medium to form a desired image (e.g., picture, chart or text).
In order for the image to be fixed to the print media so that it will not smear, the ink must be dried. The ink is dried by a combination of the solvent evaporating and the solvent absorbing into the print medium, both of which take time. Various factors control the amount of time required for a particular ink to dry. These factors include the type of print media, the quantity of solvent in an ink, the amount of ink on the print media, and ambient temperature and humidity. Ideally, the ink will be fixed to the print medium quickly to help prevent image smear, print media cockle (print media buckle toward a printhead), and print media curl (curling along at least one edge of a print media), as well as to help maximize printing device throughput.
To reduce the amount of this time, the surface of some types of print media may be specially coated to help speed drying. Other means may also be used such as special chemicals, generally know as "fixers", that are applied to print media before or after printing. Various types of heating devices may also be used to heat print media before and/or after printing. Pressure may also be applied, alone or in combination with heat from a heating device, to help reduce this amount of time.
Each of these above-described techniques have certain disadvantages. For example, specially coated print media may be relatively more expensive than uncoated print media. Fixers may become depleted during printing, resulting in no fixer being applied for the remainder of a print job, possibly causing some or all of the aforementioned problems, or the stopping of a print job to supply additional fixer, resulting in decreased printing device throughput and possible color hue shift on the print medium for which printing was halted.
Heating devices often must be warmed-up to an operating temperature which reduces initial printing device throughput. Some heating devices also require heat shielding or heat absorbing members to protect various components of a printing device from excess heat and to help dissipate heat which adds to the overall cost, size, and complexity of the printing device. In addition, such heating devices often are thermally inefficient, requiring and wasting large amounts of energy which adds to the cost of operating a printing device.
Pressure generating devices, such as pressure rollers, can cause image smear. Also, pressure generating devices add to the overall cost, size and complexity of the printing device.
An apparatus and method that decreased the amount of time required to fix ink to a print medium while avoiding the above-described problems associated with other techniques would be a welcome improvement. Accordingly, the present invention is directed to fixing ink to a print medium quickly to help prevent image smear, print media cockle, and print media curl. The present invention is also directed to helping maximize printing device throughput and minimize excessive heat generation so that the above-described heat shielding and heat absorbing members are unnecessary, thereby avoiding the above-described problems associated with such devices. The present invention is further directed to eliminating the need for pressure generating devices to help fix ink to print media, thereby also avoiding the above-noted problems associated with such devices.
An embodiment of an inkjet printing method of fixing ink to a print medium in accordance with the present invention comprises depositing ink drops on a print medium with an inkjet printhead, the ink including a solvent and the print medium including a first surface. The method additionally includes vibrating the print medium by applying ultrasonic energy to displace drops of the solvent to the first surface of the print medium to accelerate evaporation of the drops of solvent.
The above-described embodiment of a method of the present invention may be modified and include the following characteristics described below. The inkjet printing method may further comprise reducing a size of the drops of ink solvent with ultrasonic energy to accelerate evaporation of the drops of solvent. The inkjet printing method may further comprise heating the drops of ink solvent with ultrasonic energy to accelerate evaporation of the drops of solvent.
Vibrating the print medium with ultrasonic energy may include contacting the print medium. The ultrasonic energy may be applied over a predefined period of time. A fixed intensity of ultrasonic energy may be applied. A predetermined quantity of ultrasonic energy may be applied. Alternatively, a variable quantity of ultrasonic energy may be applied.
The inkjet printing method may further comprise adjusting a quantity of ultrasonic energy applied based on at least one of the following: ambient temperature, ambient humidity, print medium type, ink dry time, or an amount of ink deposited on the print medium.
An embodiment of an apparatus in accordance with the present invention for use in an inkjet printing device, the inkjet printing device configured to deposit ink on a print medium, the ink including a solvent and the print medium including a first surface, comprises an ultrasonic source configured to apply ultrasonic energy to the print medium to displace drops of the solvent to the first surface of the print medium thereby accelerating evaporation of the drops of solvent.
The above-described embodiment of an apparatus of the present invention may be modified and include the following characteristics described below. The ultrasonic source may be configured to apply ultrasonic energy to the drops of solvent to reduce a size of the drops of solvent thereby accelerating evaporation of the drops of solvent. The ultrasonic source may be configured to apply ultrasonic energy to the drops of solvent to heat the drops of solvent thereby accelerating evaporation of the drops of solvent.
The apparatus may further comprise a controller coupled to the ultrasonic source and configured to regulate the ultrasonic source thereby controlling application of the ultrasonic energy. The controller may be configured to regulate the ultrasonic source to apply ultrasonic energy over a predefined period of time. The controller may be configured to regulate the ultrasonic source to apply a fixed intensity of ultrasonic energy. The controller may be configured to regulate the ultrasonic source to apply a predetermined quantity of ultrasonic energy. The controller may be configured to regulate the ultrasonic source to apply a variable quantity of ultrasonic energy.
The apparatus may further comprise an ambient sensor coupled to the controller. In such cases, the controller is configured to utilize data from the ambient sensor to regulate the ultrasonic source.
The apparatus may further comprise a print medium sensor coupled to the controller. In such cases, the controller is configured to utilize data from the print medium sensor to regulate the ultrasonic source.
The apparatus may further comprise an ink dry-time sensor coupled to the controller. In such cases, the controller is configured to utilize data from the ink dry-time sensor to regulate the ultrasonic source.
The ultrasonic source may be positioned to contact the print medium. The apparatus may be used in a printing device.
An alternative embodiment of an apparatus in accordance with the present invention for use in an inkjet printing device, the inkjet printing device configured to deposit a ink on a print medium, the ink including a solvent and the print medium including a first surface, comprises structure for fixing ink deposited on the print medium by vibrating the print medium with ultrasonic energy to displace drops of solvent to the first surface of the print medium to accelerate evaporation of the drops of solvent. The apparatus additionally comprises structure for controlling the structure for fixing to regulate application of the ultrasonic energy.
The above-described alternative embodiment of an apparatus of the present invention may be modified and include the following characteristics described below. The structure for fixing may be configured to reduce a size of the drops of solvent to accelerate evaporation of the drops of solvent. The structure for fixing may be configured to heat the drops of solvent to accelerate evaporation of the drops of solvent.
The apparatus may further comprise structure for sensing an ambient condition and transmitting data representative of this sensed ambient condition to the structure for controlling. In such cases, the structure for controlling is configured to utilize this data to regulate the structure for fixing.
The apparatus may further comprise structure for sensing print medium type and transmitting data representative of this sensed print medium type to the structure for controlling. In such cases, the structure for controlling is configured to utilize this data to regulate the structure for fixing.
The apparatus may be used in a printing device.
Other objects, advantages, and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.